I have an E series 3D tv and i love it
Hmm this statement threw me for an interesting loop. I didn't think that the Vizio E series had 3D in the larger models, but it appears that they do. I thought the 3D E-series TVs mostly encompassed the smaller models that the M series doesn't really cover. Anyway, it looks like the E series is actually rather annoying convoluted.
I found
this page on CNET, which covers the differences in the E series models. Amazon doesn't appear to sell the E551D, which has 3D, but they
do sell the
E550i and the
E551i. The difference between those two appears to be the way they're lit. The E550i has direct lighting, which mean sit has an array of LEDs behind the entire panel. The E551i is edge-lit, which means it has LEDs around the outside that shine light inward. Edge-lit is arguably not as good as direct-lit, but direct-lit does usually result in thicker TVs.
EDIT:
Any sense of what the input lag is? Does it have a gaming mode?
If you're curious about any features, you can check out the
E550i's manual, which shows on page 28/65 (page 22 in-book) that there is a Game Mode.
Here's the
E551i manual, which also talks about Game Mode on page 29/67 (page 23 in-book).